Electric heater



Aug. 1 w. H. REYNOLDS 1,969,760

ELECTRIC HEATER Filed May 26, 1952 /5 4 Ira-l am% V////////%%//////////A IN V EN TOR.

amavwfo Patented Aug. 14, 1934 S UNETED STATES ELECTRIC HEATER William H. Reynolds, Silver Spring, Md., assignor to. American Instrument Company, Washington, D. 0., a corporation of Delaware Application May 26, 1932, Serial No. 613,724

1 Claim.

My invention relates broadly to electric heaters and more particularly to a structure of immersion type heater which may be manufactured on a large scale at low cost.

One of the objects of my invention is to provide an improved construction of tubular immersion type of electric heater which may be manufactured at low unit cost.

Another object of my invention is to provide a construction of electric heater wherein a minimum number of parts are employed for the production of a sealed type of heater element within a metallic sheath and in which the heater element is substantially insulated throughout its length from the walls of the metallic sheath and electrically connected with terminals supported on opposite ends of the sheath.

Another object of my invention is to provide a construction of terminal for the opposite ends of a tubular sheath in which means are provided for insulatingly centering a connecting member extending from the heater coil within the tubular sheath of an electric heater, at the same time establishing electrical connection With the terminal on the end of the sheath.

Other and further objects of my invention reside in the construction or" an electric heater as set forth more fully in the specification hereinafter following by reference to the accompanying drawing, in which: 7

Fig. 1 is a cross-sectional view taken through the insulated terminal for the heater of my invention and showing the connection of the sheath therewith in elevation; Fig. 2 is a cross-sectional view taken through parts of the terminal and through the sheath and showing the conductive sleeve and the manner of connection thereof with the terminal; Fig. 3 is a cross-sectional view taken through the terminal on line 3-3 of Fig. 2; Fig. 4 is a cross-sectional view through the terminal taken on line 44 of Fig. 2; Fig. 5 is a crosssectional View taken through the heating element and sheath surrounding the heating element on line 55 of Fig. 2; Fig. 6 is a cross-sectional view taken through the heating element and sheath surrounding the heating element on line 66 of Fig. 2; and Fig. 7 is a perspective view illustrating the manner in which a plurality of immersion type heaters embodying my invention may be associated with each other in an immersion bath.

The electric heater of my invention comprises heating element 1 embedded in the refractory 2 within sheath 3. A metallic sleeve 4 having a diameter which isefiectively the same as the diameter of the resistance wire constituting the heating element is applied over the end of the resistance wire forming the heating element.

The metallic sleeve 4 is clinched in position with respect to the projecting end of the heating element 1 as indicated at 4a. A terminal is applied over the end of the conductive sleeve 4 and directly against the end portion of the sheath 3. The terminal is represented as having an insulated body structure represented at 5 with an axially extending bore 6 passing therethrough. Interior- 55. ly of the insulated body structure 5 there is molded the tubular sleeve '7 having head portion 8 directly abutting against a shoulder 9 in the body structure 5. The extended end of the tubular sleeve '7 is chamfered internally at 10 to allow the entrance of the end of the conductive sheath 3. The conductive sleeve 4 is passed through the bore 6.

As illustrated in Figs. 1 and 2, the conductive sheath 3 is secured to tubular'sleeve 7 by a band of solder ll adhering between the sheath 3 and the chamfered portion 10 of the tubular sleeve 7. The conductive sleeve 4 which extends axially through the insulated body structure 5 passes directly through screw threaded member'l2 having 3 V a head 14 thereon embedded in the insulated body structure 5. The screw threaded portion 12 connected with the head portion 14 is directly engaged by nut 15 and by screw threaded bushing 16 in insulated terminal head 17. The end of the 5 conductive sleeve 4 is soldered in the end of the screw threaded portion 12 as shown at 18. The

seal between the terminal and the end of the sheath 3 is such that the entrance of moisture into the resistance coil is prevented. The sheath 3 may be bent to any suitable shape such as the loop shape indicated at 19 in Fig. 7. Several turns may be formed in the tubular sheath 3 as the sheath is sufficiently flexible and pliable as a result of annealing in the process or" manufacture to allow formation of the heater in desired shapes. The heater may be shipped in the form of a longitudinally extending rod with the electric terminals in position on opposite ends thereof subject to be bent to shape by the user in accordance with the requirement of the user.

Fig. 3 shows in cross-section the manner in which the screw threaded member 12 receives the conductive sleeve 4, which in turn surrounds the extension 1 onthe heating element.

In Fig. 4 I have shown a cross-sectional view taken on line 44 of Fig. 2 and illustrating the relation of the insulated body structure 5 with respect to the sleeve 7 and the conductive sleeve 4, and. showing the manner in which the con- 1 ductive sleeve 4 is spaced from the internal wall structure of bore 6 and tubular sleeve 7. The head 8 of the sleeve 7 is shown in dotted lines in Fig. 4.

In Fig. 5 I have shown the manner in which the turns of the heater coil 1 are insulatingly supported by pulverized insulation material 2 with respect to the interior wall of the tubular sheath 3.

In Fig. 6 the manner in which conductive sleeve 3 is clinched at 4a against the extending end of the heater coil 1 for insuring good elec trical and mechanical connection between the,

heater coil 1 and the end of the heater coil is shown.

In Fig. '7 I have shown a method of applying my invention wherein a multiplicity of heaters may be concentrically disposed in, spaced rela tion and submerged in a bath contained within" Heater 21 has terminals 24 at the upper ex- EIeat'er 22 has terminals 25 at the.

tremities. upper extremities thereof. The several heaters are supported through a bracket member 26 on the interior ofthetanl: 20in sucharrangement that the several heaters operate immersion heaters beneaththe fluid contents 27- of the tank 20. The heatersarranged in this mannerhave been found to be very efficientin maintaining a water or oilbath at constant temperature.

The heaters of my invention are manufactured for operation on the lighting circuit. Either alternating or direct current suppiy may be utilized for energizing the heater element. The heater may be associated with various types of 4 'automatic regulators for controlling the time period of energization in accordance with the temperature of the bath.

The structure of the device of my invention has been found to be highly efficient and successful in operation. While I have described the preferred construction of immersion heater of my invention, I desire that it be understood that modifications may be made and that no limitations upon my invention are intended other than are imposed by the scope of the appended claim.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

A terminal for an electric hea er comprising an elongated body of insulation, a tubular nipple embedded for a portion of its length in one end portion of said body and having a portion projecting outwardly therefrom to iit about a casing of a heater, said nipple having a flared mouth at its outerend whereby the nipple may be fitted about an end of a heater casing and firmly secured by solder disposed about the casing and extending into the mouth of the nipple, a tubular post partially embedded the other end portion of said body in alignment with said nipple and projecting from the body, said body having a bore between inner ends of the post and nipple, bores of the body and nipple being of greater diameter than the hereof the post, a conductor having an end portion passed through the nipple and post in spaced relation to walls of the nipple and body and having snug fitting conductive engagement 10 5 with walls of the post, the outer end or" said conductor being soldered to walls of the post, inner ends'cf the post and nipple being formed with enlarged heads non-circular in cross section'to I prevent rotation of the same in the body and the post externally threaded, an abutment washer threaded upon said post and bearing against the adjacent-end of said body, and 'a binding cap having an internally threaded core for threaded engagement with the screw threaded post.

WILLIAM n, REYNOLDS. 

